Equilibrium mode distribution

About: Equilibrium mode distribution is a research topic. Over the lifetime, 928 publications have been published within this topic receiving 14939 citations.

Selective excitation of step-index fiber modes

Abstract: Measuring the power distribution among transverse modes of coherent light in optical fibers and excitation of transverse modes or modal groups in a fiber are of practical significance for development and investigation of fiber lasers, sensors and fiber communication lines. The feasibility of mode generation in a step-index optical fiber using binary phase diffractive optical elements (DOEs) is studied. Modes different from the principal mode are selectively excited in the optical fiber using the binary phase DOEs. It is also reasonable to make a computer simulation of mode excitation to predict the behavior of optical system. Simulation results prove theoretical derivations on characteristics of mode excitation. These results are also in a good concordance with experimental ones.

Efficient mode coupling between a few-mode fiber and multi-mode photonic chip with low crosstalk.

Abstract: The mode-division multiplexing technology has been developing slowly in the field of fiber-chip-fiber optical interconnects, mainly limited by the inefficient mode coupling between few-mode fiber and multi-mode photonic chip. Here we propose and design a multi-mode coupler composed of tapered few-mode fiber and silicon integrated multistage waveguide tapers, which allows the direct coupling between high-order fiber modes and high-order waveguide modes with high coupling efficiency and low crosstalk. Based on the edge coupling scheme, the six linear polarization modes (LP01x/y, LP11a x/y, LP11bx/y) in few-mode fiber are firstly coupled into the integrated waveguide with low insertion loss, then the input modes are converted to the desired waveguide modes (TE0, TE1, TE2, TM0, TM1, TM2) with low mode crosstalk relying on the mode evolution principle. The obtained results show that the coupling efficiency is higher than 87%, while for the mode conversion process, the efficiency is higher than 99% and the mode crosstalk is lower than -25 dB. The favorable performance achieved may open new perspectives for diverse mode-division multiplexing applications, enabling efficient capacity scaling in fiber-chip-fiber optical interconnects and optical communication systems.

A Tapered Metallic Baffle to Mode Converter With Mode Transmission Capability

Abstract: Ac ompact to mode converter having a linear shape and high conversion efficiency is proposed. A ta- pered metallic baffle at the centre and rectangular ridges on both sides of the baffle at the inner walls of waveguide are placed to achieve wide mode conversion bandwidth. The mode converter is designed and simulated for an operating frequency of 3.2 GHz. The mode is converted to mode over the 2.95-3.24 GHz frequency band and the mode is transmitted through the waveguide over the same frequency range, both with efficiency higher than 90%. Electric field calculations show that the mode converter is capable of handling Giga-Watt level input signals. The modeconversionwasverifiedexperimentallybymeasuringthefar- field radiation pattern at the output. The proposed mode converter has the advantage of compactness and wide bandwidth and is also useful for the case when the input to the mode converter has a mode component in addition to the mode.

Array waveguide diffraction grating type optical multiplexer/demultiplexer

Abstract: An object of this invention is to cancel a polarization dependence of a transmission center wavelength due to the waveguide birefringence in an array waveguide and a slab waveguide in an array waveguide diffraction grating type optical multiplexer/demultiplexer filter applied for optical communication, particularly, wavelength split multiplexing system. In order to achieve the object of this invention, a polarization mode convertor converts the TE mode in a waveguide to the TM mode and the TM mode to the TE mode. This conversion function makes it possible to cancel the polarization dependence of the transmission center wavelength due to the waveguide birefringence in the array waveguide and the slab waveguide in front of and behind the polarization mode convertor.

Theoretical analysis of optimal quasi-phase matched second harmonic generation waveguide structure in LiTaO3 substrates

Abstract: Based on the QPM structure and the coupled-mode theory, the maximum SHG conversion efficiency of QPM-SHG waveguides in LiTaO3 substrates is analyzed by optimizing the mode confinement and the mode overlap factors. For TM00(ω)-to-TM00(2ω) conversion with a non-square shaped domain inversion QPM structure, the mode confinement and mode overlap factor are dependent not only on the optical field distribution for the fundamental and the SH waves in the waveguide, but also on the domain inversion shape. With the assumption that the refractive index profile of an annealed, proton exchanged LiTaO3 channel waveguide is an exponential decay function in the depth direction, and a Gaussian function in the width direction, the analytical expression of the optical field distribution for the lowest order mode can be obtained. By considering both a non-Gaussian field distribution and a non-square shaped domain inversion structure, the theoretical values for achieving the optimal QPM-SHG waveguide structure are determined.